1. Field of the Invention
The present invention is directed to nuclear power reactors. More specifically, this invention is related to a safety device for nuclear power reactors.
2. Description of the Prior Art
In a conventional nuclear power reactor system, the reactor and the steam generator connected thereto are situated within a containment wall. The steam so generated is fed via a pipe through the containment wall to drive a steam turbine for power generation. Typically, to guard against over pressurization within the pipe, steam safety valves and steam release valves are put on line. Thus, in the event of a rupture in the pipe, the main steam isolation valve is closed and high pressure steam is released or dumped into the surrounding atmosphere through the steam release valves. Such a release into the atmosphere runs the risk of releasing radioactive materials into the air, particularly if some of the tubes in the steam generator in the nuclear reactor should rupture simultaneously. Hence, there is a need for a passive emergency steam dumping system to be used in connection with nuclear reactors. By passive, it is meant devices which will perform its assigned duty even when electric power is not available.
Furthermore, when there is a total loss of electric power coupled with a steam line break, removal of the residual heat in the steam generator and the emergency auxiliary feedwater system will need an uninterrupted power source to circulate cold water to condense the steam and to supply the auxiliary feed water. Although emergency generators can be used as a back-up in case of power failure, it would be highly preferable to have a passive system whereby the energy in the high pressure steam from the steam generator is converted into mechanical energy for heat removal and circulation of emergency feedwater. Since passive systems do not require an energy source as a driving force, the presence of such a passive system for use during power failures is clearly desirable.